Electronic drivers have become a common means for driving modern lighting sources, typically Light Emitting Diodes (LEDs). Such a drive is sometimes connected to a traditional triac-based lighting dimmer, denoted herein “external dimmer” or “dimmer”, which is fed by the AC mains system. In this case undesirable interference might occur.
One interference type is a current surge that typically occurs at the onset of the dimming angle. This surge is part of an oscillation that develops on the driver's input Radio Frequency Interference (RFI) filter and input capacitance when excited by the external dimmer's abrupt transition to the triac conducting mode. This interference would typically disrupt the operation of the driver and the dimmer. Another problem arises, in the case of an external electronic dimmer, when the driver's input capacitance charges during the external dimmer's conducting period and prevents a voltage drop from developing on the external dimmer's control circuits during the dimmer cutoff period.
Adding a series resistor at the driver's input is a known technique used in the art for mitigating the above interference. However, such a series resistor reduces the input voltage of the driver and is not effective enough for external electronic dimmer. Connecting a resistor parallel to the driver input is also a known technique, however power wasteful.